Selective multiple-media access control

ABSTRACT

A communication system and method includes receiving payload data of first and second media access control (MAC) frames. A MAC-level protocol is identified in response to the indication of the selected network for each of the first and second MAC frames. The payload data of the first and second MAC frames is transmitted and/or received across respective networks transmitted using, for example, power line communications signals over a common communications medium. The common communications medium is operable for carrying signals of a plurality of networks.

CLAIM OF PRIORITY

This application for patent claims priority to U.S. ProvisionalApplication No. 61/891,755 entitled “DUAL MAC” filed Oct. 16, 2013 inthe United States Patent and Trademark Office, wherein the applicationlisted above is hereby fully incorporated by reference herein for allpurposes.

BACKGROUND

Utilities are increasingly using networked meters to reducemeter-reading costs and to monitor user consumption in real-time.Networking applications such as power line communications (PLC)typically use the TCP/IP (transmission control protocol/internetprotocol) stack architecture. The conventional MAC (medium accesscontrol) layer is part of a network protocol layer that controls theaccess to a communications channel. In conventional networkarchitectures, each protocol stack is associated with a single network.The conventional MAC layer is normally assigned a unique address toidentify itself in various communications within the network. Theconventional MAC layer includes a protocol stack that can communicatewith resources within the network using the assigned address. However,such conventional network protocols are not well suited forcommunications over different networks using different protocols.

SUMMARY

The problems noted above can be addressed in a communication system andmethod operable to receive, for example, payload data of first andsecond media access control (MAC) frames. A MAC-level protocol isidentified in response to the indication of the selected network foreach of the first and second MAC frames. The payload data of the firstand second MAC frames is transmitted and/or received across respectivenetworks transmitted using, for example, power line communicationssignals over a common communications medium. The common communicationsmedium is operable for carrying signals of a plurality of networks.

This Summary is submitted with the understanding that it is not be usedto interpret or limit the scope or meaning of the claims. Further, theSummary is not intended to identify key features or essential featuresof the claimed subject matter, nor is it intended to be used as an aidin determining the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an illustrative electronic device in accordance withexample embodiments of the disclosure.

FIG. 2 is a block diagram illustrating a network architecture havingselective media access control in accordance with various embodiments ofthe disclosure.

FIG. 3 is a block diagram illustrating nodes of a network havingselective media access control in accordance with various embodiments ofthe disclosure.

FIG. 4 is a block diagram illustrating a split network stack havingselective media access control in accordance with various embodiments ofthe disclosure.

FIG. 5 is a block diagram illustrating a selective media accesscontroller in accordance with various embodiments of the disclosure.

FIG. 6 is a signal diagram illustrating a frame for selective mediaaccess in accordance with various embodiments of the disclosure.

FIG. 7 is a block diagram illustrating an alternative selective mediaaccess controller in accordance with various embodiments of thedisclosure.

FIG. 8 is a signal diagram illustrating PHY layer protocolidentification in selective media access control in accordance withvarious embodiments of the disclosure.

DETAILED DESCRIPTION

The following discussion is directed to various embodiments of theinvention. Although one or more of these embodiments may be preferred,the embodiments disclosed should not be interpreted, or otherwise used,as limiting the scope of the disclosure, including the claims. Inaddition, one skilled in the art will understand that the followingdescription has broad application, and the discussion of any embodimentis meant only to be example of that embodiment, and not intended tointimate that the scope of the disclosure, including the claims, islimited to that embodiment.

Certain terms are used throughout the following description—andclaims—to refer to particular system components. As one skilled in theart will appreciate, various names may be used to refer to a componentor system. Accordingly, distinctions are not necessarily made hereinbetween components that differ in name but not function. Further, asystem can be a sub-system of yet another system. In the followingdiscussion and in the claims, the terms “including” and “comprising” areused in an open-ended fashion, and accordingly are to be interpreted tomean “including, but not limited to . . . .” Also, the terms “coupledto” or “couples with” (and the like) are intended to describe either anindirect or direct electrical connection. Thus, if a first devicecouples to a second device, that connection can be made through a directelectrical connection, or through an indirect electrical connection viaother devices and connections. The term “portion” can mean an entireportion or a portion that is less than the entire portion.

FIG. 1 shows an illustrative computing device 100 in accordance withpreferred embodiments of the disclosure. For example, the computingdevice 100 is, or is incorporated into, an electronic system 129, suchas a computer, electronics control “box” or display, communicationsequipment (including transmitters), or any other type of electronicsystem arranged to generate radio-frequency signals.

In some embodiments, the computing device 100 comprises a megacell or asystem-on-chip (SoC) which includes control logic such as a CPU 112(Central Processing Unit), a storage 114 (e.g., random access memory(RAM)) and a power supply 110. The CPU 112 can be, for example, aCISC-type (Complex Instruction Set Computer) CPU, RISC-type CPU (ReducedInstruction Set Computer), MCU-type (Microcontroller Unit), or a digitalsignal processor (DSP). The storage 114 (which can be memory such ason-processor cache, off-processor cache, RAM, flash memory, dataregisters, flip-flops, disk storage, and the like) stores one or moresoftware applications 130 (e.g., embedded applications) that, whenexecuted by the CPU 112, perform any suitable function associated withthe computing device 100.

The CPU 112 comprises memory and logic that store information frequentlyaccessed (e.g., written to and/or read from) from the storage 114. Thecomputing device 100 is often controlled by a user using a UI (userinterface) 116, which provides output to and receives input from theuser during the execution the software application 130. The output isprovided using the display 118, indicator lights, a speaker, vibrations,and the like. The input is received using audio and/or video inputs(using, for example, voice or image recognition), and electrical and/ormechanical devices such as keypads, switches, proximity detectors,gyros, accelerometers, and the like. The CPU 112 is coupled to I/O(Input-Output) port 128, which provides an interface that is configuredto receive input from (and/or provide output to) networked devices 131.The networked devices 131 can include any device (including key fobs orbase-station control modules that are electronically paired with thecomputing device 100) capable of point-to-point and/or networkedcommunications with the computing device 100. The computing device 100is optionally coupled to peripherals and/or computing devices, includingtangible, non-transitory media (such as flash memory) and/or cabled orwireless media. These and other input and output devices are selectivelycoupled to the computing device 100 by external devices using wirelessor cabled connections. The storage 114 is accessible, for example, bythe networked devices 131.

The CPU 112 is coupled to I/O (Input-Output) port 128, which provides aninterface that is configured to receive input from (and/or provideoutput to) peripherals and/or computing devices 131, including tangible(e.g., “non-transitory”) media (such as flash memory) and/or cabled orwireless media (such as a Joint Test Action Group (JTAG) interface).These and other input and output devices are selectively coupled to thecomputing device 100 by external devices using wireless or cabledconnections. The CPU 112, storage 114, and power supply 110 can becoupled to an external power supply (not shown) or coupled to a localpower source (such as a battery, solar cell, alternator, inductivefield, fuel cell, capacitor, and the like).

The disclosed selective multiple-media access control techniquesinclude, for example, an architecture where a physical layer (forcontrolling communication across a communications medium) is sharedbetween multiple networks via one or more portions of a (e.g.,horizontally) split MAC protocol stack associated with the physicallayer. The illustrated embodiments include architectures thatdemonstrate operation over two networks as an example and the disclosedtechniques can be extended to select amongst two, three, four, or morenetworks by selecting a portion of a split MAC protocol stack associatedwith one of the various networks.

The computing system 100 includes a smart meter 138 that is arranged toreceive and transmit packet-based communications based on the OSI(open-systems interconnection) model (e.g., layered protocol stack). Thesmart meter 138 is arranged to provide power line communications (PLC)using a selective MAC (media access control) controller for performingMAC-level protocols and for selecting a physical layer over which thepacket-based communications are to be sent and received.

Conventional devices such as switches, routers and gateways are arrangedto share protocol layers for different networks. Such devices arecapable of evaluating the source of the packet (from informationreceived from the interface through which the packet is received) andretransmitting (e.g. forwarding) the received packet using a selectedoutput interface that is selected as being appropriate on the basis of aforwarding strategy that is associated with the packet. However, theconventional devices (such as switches, routers and gateways) are notnormally individual entities that are a part of a member network itself,but are special devices that are dedicated to serve as a bridge betweendifferent networks. Such bridge devices normally include separatenetwork stacks for each different network interface.

FIG. 2 is a block diagram illustrating a network architecture havingselective media access control in accordance with various embodiments ofthe disclosure. Although the disclosed architecture can be applied tovirtually any stack-based network, the G3-PLC protocol-based PLC networkis used herein for purposes of illustration. Generally described, theG3-PLC standard is directed towards power line communications.

The network stack 200 is a network stack organized in accordance with aG3-PLC protocol stack. The network stack 200 is illustrated as havingfive layers: the physical layer, the MAC layer, the network layer, thetransport layer, and the application layer. The physical layer includesphysical layer (PHY) 210 that is coupled to a communication medium viacoupler (CPL) 202. The MAC (media access control) layer includes the MACsublayer 220, the 6LoWPAN (IPv6 over low power wireless personal areanetworks) adaptation sublayer 222, and the 6LoWPAN/LOAD (IPv6 ad hocon-demand distance vector routing) adaptation sublayer 224. The networklayer includes the compressed IPv6 (Internet protocol version six) layer230. The transport layer includes the UDP (user datagram protocol) layer240. The application layer includes the wrapper 250, the COSEM(companion specification for energy metering) application layer 260, theCOSEM interface model 270, the TFTP (trivial file transfer protocol)252, the SNMP (simple network time protocol) 254, and files 272. Theinitialization manager (INIT MNGT) 256 is operable for initializing thelogical states of the various layers and sublayers.

The MAC sublayer 220 is normally responsible for granting channel accessand for filtering frames using network addresses. In an example G3-PLCnetwork, each node joins to a personal area network (PAN) identified byan associated PAN identifier (PAN ID). The MAC sublayer 220 receivespacket frames from the PAN and filters the frames in accordance with thePAN ID and the MAC sublayer 220 address and directs the filtered framesto one of the MAC sublayers 222 and 224 (e.g., as described below withreference to 6LoWPAN and 6LoWPAN/LOAD MAC sublayers 424 and 428 of FIG.4). The MAC sublayer 220 transmits the filtered frames to higher levelsof the stack that contains the MAC sublayer 220, so that the higherlayers (such as the network layer, transport layer, and applicationlayer) of the appropriate stack receive and process the filtered packetframes associated with a PAN network as identified by a PAN ID.

FIG. 3 is a block diagram illustrating nodes of a network havingselective media access control in accordance with various embodiments ofthe disclosure. The neighborhood 300 includes houses 310, 320, and 330.For purposes of illustration, three houses are shown: the neighborhood300 optionally includes more or less houses. The neighborhood 300includes a portion (including the entire portion) of a neighborhood ofhouses served by a utility 340 (e.g., power, gas, and water utilities,as well as any utility providing metered access to a suppliedcommodity).

The house 310 includes a selective media access control smart meter 312,a personal area network (such as a home area network 314), and a homeenergy management system (HEMS) controller 316. The HEMS controller 316is arranged for communicating with the a selective media access controlsmart meter 312 using protocol route B via HAN 314 and power line 302Route B is discussed below, for example, with respect to FIG. 4 below.The HAN 314 is a network such as a home network that is operable forcontrolling home appliances using power line communications. Theselective media access control smart meter 312 is operable forcommunicating with utility 340 using protocol route A (e.g., which issuitable for longer-travelled and faster-data-rate communications thanroute B) across power line 302. Route A is discussed below, for example,with respect to FIG. 4.

The house 320 includes a selective media access control smart meter 322,a personal area network (such as a HAN 324), and a HEMS controller 326.The HEMS controller 326 is arranged for communicating with the aselective media access control smart meter 322 using protocol route Bvia HAN 324 and power line 302. The HAN 324 is a network such as a homenetwork that is operable for controlling and monitoring home appliancesusing power line communications. The selective media access controlsmart meter 322 is operable for communicating with utility 340 usingprotocol route A across power line 302.

The house 330 includes a selective media access control smart meter 332,a personal area network (such as a HAN 334), and a HEMS controller 336.The HEMS controller 336 is arranged for communicating with the aselective media access control smart meter 332 using protocol route Bvia HAN 334 and power line 302. The HAN 334 is a network such as a homenetwork that is operable for controlling home appliances using powerline communications. The selective media access control smart meter 332is operable for communicating with utility 340 using protocol route Aacross power line 302.

In an example scenario, the smart meter 312 of the house 310 serves asboth as a node of a “route A” network (e.g., for communicating withutility 340 processors) and as a node of HAN 314 (e.g., for controllingand monitoring home appliances). In such a situation the smart meter 312is both part of the utility network 302 and also the personal areanetwork 314. When the same node (such as smart meter 312) attempts toaccess the two different networks (such as utility network 302 and PAN314), two G3-PLC protocol stacks are used, with each stack beingassociated a separate network. In the example scenario, the smart meter312 is a network entity of both the utility network 302 and the HAN 314.

FIG. 4 is a block diagram illustrating a split network stack havingselective media access control in accordance with various embodiments ofthe disclosure. The home-energy management network 400 includes a smartmeter 470 and a HEMS 480. The smart meter 470 includes a split networkstack 406 is that arranged for performing power line communicationsusing differing MAC-level protocols for communications across power line402. For example, the split network stack 406 is operable forcommunicating with the utility 404 (via Route A) and for communicatingwith HEMS 480 (via Route B). Accordingly, route A and route B aredifferent paths through the MAC layer by using the same (or different)MAC-level protocols that operate over two different networks. The twodifferent networks communicate over a common power line 402. In suchcases, a node belonging to one network will typically filter out theframes received from another network via the common power line 402.

The split network stack 406 is a network stack having a split-MAC layerprotocol stack architecture. The split network stack 406 includes MAClayer that is split (e.g., vertically and horizontally) at differentpoints for performing and controlling communication over two networks(e.g., across the same physical medium) via Route A and Route B. A firstportion (e.g., 6LoWPAN/LOAD 428) of the split MAC layer is associatedwith lower layers of the split networks stack 406. A second portion(e.g., 6LoWPAN 424 and UMAC 426) of the split MAC layer is associatedwith higher layers of the split network stack 406.

The split network stack 406 includes coupler 408, orthogonalfrequency-division multiplexing physical layer (OFDM PHY) 410, IEEEstandard 802.15.4 (lower MAC) layer 420, 6LoWPAN LOAD (IPv6 ad hocon-demand distance vector routing) sublayer 428, UMAC (universal-hashingmessage authentication code) layer 426, 6LoWPAN sublayer 424, compressedIPv6 (Internet protocol version 6) layer 430, RPL (routing protocol forlow-power and lossy networks) layer 438, compressed UDP (user datagramprotocol) 440, and application layer (APP) 457.

The split MAC layers (424, 426, 428) of the split network stack 406 areoperable for storing and accessing the PAN ID of the associated PANnetwork and the MAC address associated with each communication receivedfrom or transmitted to each PAN. The lower MAC layer 420 of the splitnetwork stack 406 is operable for selecting a PAN for transmitting thepackets received from higher layers. The PAN (e.g., together with theassociated route A or route B) is selected in accordance with the MACaddress and PAN ID associated with the PAN packets to-be transmitted.The packets to-be transmitted are transmitted over the power line 402,which is shared by different PANS (including the selected PANS).

Upon receiving a packet transmitted across the power line 402, the splitMAC layer of the split network stack 406 is arranged for identifying thenetwork (e.g., in accordance with the PAN ID and MAC address associatedwith the received packed) of the and routing the (e.g., payload of the)received packet to the appropriate higher layer.

In the illustrated architecture, the higher layers (e.g., such as layers430 and 440) of applications respectively use G3-PLC protocols but withdifferent routing protocols (e.g., the LOAD or RPL protocols). However,the disclosed methods are operable to handle devices that operate overdifferent networks (which optionally operate with different networkprotocols) in accordance with the different network protocol layers thatare above the MAC level.

Various devices (e.g., network entities) coupled to the power line 402access the split MAC layer of split network stack 406 to share achannel-access mechanism (e.g., carrier sense multiple access withcollision avoidance, or “CSMA/CA”) and the PHY layer to access at leasttwo different networks that use the power line 402 as the PHY layer. Inan embodiment, the split MAC layers (424, 426, 428) of the split networkstack 406 allow the protocol stack to be implemented in the samesubstrate (e.g., monolithic integrated circuit), which reduces systemcost and/or decreases power dissipation.

FIG. 5 is a block diagram illustrating a selective media accesscontroller in accordance with various embodiments of the disclosure. Theselective media access controller 500 is optionally implemented in afirst substrate 502 (e.g., where the application and other higher layerfunctions are implemented in a second, different substrate while the MACand PHY layer functions are implemented in the first substrate). Theselective media access controller 500 is optionally arranged as discretelogic, memory, a microprocessor, and/or combinations thereof.

The selective media access controller 500 is arranged for performing thefunctions of encryption/decryption, segmentation/reassembly of packets,channel access (e.g., including arbitration), and address filtering. Invarious embodiments, a single selective media access controller 500optionally is operable for performing the MAC and PHY layer functions ofwith encryption/decryption and segmentation and reassembly of packetsfor only one of the two networks (e.g., where each network isrespectively accessed via route A or route B in FIG. 4 discussed above),and a second controller optionally is operable for performing the MACand PHY layer functions of with encryption/decryption and segmentationand reassembly of packets for the other one of the two networks.However, the selective media access controller 500 is operable toperform (e.g., both the higher-level) functions of channel access, andaddress filtering for both such networks.

The selective media access controller 500 is operable for performingdual MAC functions (e.g., for controlling access to the physical layerof two networks). The dual MAC functions optionally have multiple (e.g.,concurrent) active sessions with a network entity that includes theselective media access controller 500. The access manager 524 isoperable for performing channel-access (e.g., CSMA/CA) functions underthe control of the MAC TX (transmit) manager 528.

In response to the selective media access controller 500 receivingframes from higher layers, the access manager 524 stores the receivedframes (e.g., as entries 544 a, 544 b, 544 c, through 544 n) in a commonqueue (e.g., MBX Q 544). The packet scheduler 542 schedules the storedframes for transmission. The tagger 580 of the MAC TX manager 528generates a network tag such as a tag identifier for each stored framesuch that the access manager 524 is able to identify the source of(e.g., the application initiating) each frame stored in the common queueand/or identify a network over which the received frame is transmittedand received. A tag identifier (e.g., tags 546 a, 546 b, 546 c, through546 n) is optionally stored in the MBX Q 544 in association with eachstored frame entry (e.g., 544 a) such that, for example, the tagidentifier is located and retrieved in response to a query using anindication of the identifier of the associated stored frame. Anindication of the tag identifier is optionally stored (e.g., in place ofthe tag itself) by storing each frame in a location of the queue 544 (orin a separate queue as in the queues 744 and 757 of FIG. 7, discussedbelow) that is associated with a particular protocol. The access manager524 performs channel access sequentially for each of the packets in thequeue and ensures that each packet is transmitted. The access manager524 may treat with same priority or different priorities based on thetag.

In response to receiving a frame, the MAC Rx Manager 526 tags the packet(that includes the received frame) in response to the identity of theincoming network (which can be determined through network addressidentifiers such as the PAN ID carried by the frame). The packet can betagged with an indication of the network such that the network can beidentified by the tag itself. The network can be any network operating(at least) at a MAC level (e.g., the network optionally includesprotocols at higher layers). The selective media access controller 500then passes the frame to the corresponding higher layer stack forfurther processing.

After receiving a frame from the PHY layer, the MAC RX (receiver)manager 526 examines the header information of the packet (that includesthe received frame) to determine the PAN ID and the “short” address (MACaddress) contained within the packet. The dispatcher 560 is arranged fordetermining whether both the PAN ID (e.g., which identifies which PAN)and short address (e.g., which identifies a node within the identifiedPAN) are associated with broadcast addresses. When both the PAN ID andshort address are associated with broadcast addresses, the dispatcher560 is operable for forwarding the received frame to both the MAC higherlayers (e.g., 6LoWPAN 424 and 6LoWPAN LOAD 428). When both the PAN IDand short address are not associated with broadcast addresses, thedispatcher 560 is operable for forwarding the received frame to theappropriate higher layer as identified by the PAN ID and short address(or, e.g., dropped if it does not identified as being associated withthe device that includes the selective media access controller 500). Forunicast addresses, the dispatcher 560 forwards the received frame to theappropriate higher layer as identified by the PAN ID and short address.

The state machine 540 is a controller operable for controlling variousaccess manager 524 functions. For example, the controlled functionsinclude performing CSMA/CA for access to the PHY layer, virtual carriersensing (VCS) using VCS timer 546, and performing back-off channelaccess using timer 748. The state machine 540 is operable forcontrolling various access manager 524 functions that are accessed viaeither of the two protocols (e.g., conducted through Route A or Route Bof split network stack 406).

Accordingly, the selective media access controller 500 is operable forperforming different roles for the different networks (e.g., a firstrole in a first network and a second role in a second network). Forexample, the selective media access controller 500 using a splitprotocol stack can assume the role of a PAN coordinator (e.g., server)in a first network (e.g., via route B) with which the home energymanagement system (HEMS) device is coupled. At the same time (forexample), the selective media access controller 500 is operable torespond as a controlled device (e.g., client) with respect to theutility network such that a utility can control the selective mediaaccess controller 500 in a second network (e.g., via route A) that usesthe same physical medium as the first network. Accordingly, a deviceincorporating the selective media access controller 500 can operate indiffering roles in differing networks while operating over the samesplit protocol stack.

FIG. 6 is a signal diagram illustrating a frame for selective mediaaccess in accordance with various embodiments of the disclosure forsignaling from/to higher layers. Frame 600 includes various fieldsincluding the message type 610, reserved 622, interface identifier 624,sequence number (SEQ NO) 626, message payload length 630, messagepayload 640, message header CRC (cyclical redundancy check) with 650,and message payload CRC 660 fields. The interface identifier 624 fieldoccupies two bits (e.g., repurposed from a conventional reserved field)for identification of the source (e.g., from a particular protocol path)of a received frame 600. For example, the two-bit-long interfaceidentifier 624 field identifies up to four sources of the frame receivedfrom a higher layer in the protocol stack. In accordance with theexample of FIG. 4, an interface identifier 624 field value of 0 is usedto identify a Route A network, and an interface identifier 624 few ofthe value of 1 is used to identify a Route B network. The bit length ofthe interface identifier 624 field is optionally increased foridentification of more than four sources (e.g., which are accessed viahigher layer protocol stacks).

FIG. 7 is a block diagram illustrating an alternative selective mediaaccess controller in accordance with various embodiments of thedisclosure. The selective media access controller 700 is optionallyimplemented in a first substrate (e.g., where the application and otherhigher layer functions are implemented in a second, different substratewhile the MAC and PHY layer functions are implemented in the firstsubstrate). The selective media access controller 700 is optionallyarranged as discrete logic, memory, a microprocessor, and/orcombinations thereof.

The selective media access controller 700 is operable for performingparallel CSMA/CA functions such that two channel access mechanisms areperformed simultaneously (e.g., overlapping in time) for differentnetworks. For example, the different networks each typically havedifferent higher protocol layers that receive calls from the selectivemedia access controller 700. The selective media access controller 700is operable to perform co-ordination between the two channel accessmethods to avoid (e.g., time-consuming) access collisions between thetwo transmissions associated with each channel access method.

The selective media access controller 700 is operable for performingdual MAC functions (e.g., for controlling access to the physical layerof two networks). The dual MAC functions optionally have multiple (e.g.,concurrent) active sessions with a network entity that includes theselective media access controller 700. The access manager 724 isoperable for performing channel-access (e.g., CSMA/CA) functions for afirst network under the control of the MAC TX (transmit) manager 728.

In response to the selective media access controller 700 receivingframes from a first application, the access manager 724 stores thereceived frames from higher layers (e.g., as entries 744 a, 744 b, 744c, through 744 n) in a common queue (e.g., MBX Q 744) of a channelaccess controller 741. The packet scheduler 742 schedules the storedframes for transmission. The tagger 780 of the MAC TX manager 728generates a tag identifier for each stored frame such that the accessmanager 724 is able to identify the source of (e.g., the applicationinitiating) each frame stored in the common queue. A tag identifier isoptionally stored in the MBX Q 744 in association with each stored frameentry (e.g., 744 a) such that, for example, the tag identifier islocated and retrieved in response to a query using an indication of theidentifier of the associated stored frame. An indication of the tagidentifier is optionally stored (e.g., in place of the tag itself) bystoring each frame in a location of the queue 744 (or in a separatequeue as in the queues 744 and 757) that is associated with a particularprotocol.

In response to the selective media access controller 700 receivingframes from a second application, the access manager 724 stores thereceived frames from higher layers (e.g., as entries 754 a, 754 b, 754c, through 754 n) in a common queue (e.g., MBX Q 754) of a channelaccess controller 751. The packet scheduler 752 schedules the storedframes for transmission. The tagger 780 of the MAC TX manager 728generates a tag identifier for each stored frame such that the accessmanager 724 is able to identify the source of (e.g., the applicationinitiating) each frame stored in the common queue. A tag identifier isoptionally stored in the MBX Q 754 in association with each stored frameentry (e.g., 754 a) such that, for example, the tag identifier islocated and retrieved in response to a query using an indication of theidentifier of the associated stored frame.

In response to receiving a frame received as a response to a callbackroutine, the access manager 724 is operable for routing the receivedframe. The MAC TX manager 724 is operable for retrieving the tag (e.g.,associated with the store frame used to initiate the callback routine)and for using to the retrieved tag to send the received frame to theassociated half (e.g., route A or route B) of the split MAC layer.

The state machine 740 is a channel access controller operable forcontrolling various access manager 724 functions pertaining to the firstapplication operating over one network (Route A or Route B). Forexample, the controlled functions include performing CSMA/CA for accessto the PHY layer, virtual carrier sensing (VCS) using VCS timer 746, andperforming back-off channel access using timer 748.

The state machine 750 is similar to the state machine 740, except thatthe state machine 750 is operable to perform the various functions withrespect to the second application operating over the other network (theother of Route A or Route B). For example, the state machine 750performs CSMA/CA functions (e.g., using back-off timer 758 and VCS timer756) in accordance with protocols associated with the secondapplication. The state machine 740 and the state machine 750 aremutually operable to share state information between the state machinessuch that, for example, CSMA/CA functions can be interleaved to avoidcollisions and improve network throughput.

For example, the state machine 740 and the state machine 750 areoperable to perform CSMA/CA functions concurrently with each maintainingits own VCS timer (e.g., 748 and 758) and back-off (e.g., 746 and 756)mechanisms. To avoid collisions (e.g., attempting to transmit framesthat would otherwise have transmissions times that would overlap), stateinformation is exchanged between the two channel access controllers 741and 751. When a second channel access controller (e.g., channel accesscontroller 751) is scheduled to transmit a frame, the second channelaccess controller accesses state information of the first channel accesscontroller to determine whether a transmission of the frame by thesecond channel access controller would overlap (e.g., interfere) with ascheduled transmission of the first channel access controller. Likewise,the first channel access controller is operable to access the stateinformation of the second channel access controller to determine whethera transmission of the frame by the first channel access controller wouldoverlap (e.g., interfere) with a scheduled transmission of the firstchannel access controller. When such a (e.g., potential) overlap isdetected, the transmission of the later scheduled frame is deferred to alater time (e.g., in which no overlap would occur) to avoid atransmission collision. Accordingly, the frame scheduled to transmitfirst is permitted to proceed without interruption (e.g., whichincreases the effective bandwidth of communications through theselective media access controller 700), and the later scheduled frame isrescheduled to a time that is after the completion of the transmissionof the earlier frame.

In various embodiments, priority is assigned using other factors (suchas the network used, the application making the call for which the frameis to be transmitted, network loads, token passing, and the like) bydirecting the lower-priority channel to reschedule to a later time.Typically, the lower-priority channel is directed to reschedule to alater time if the transmission of the lower-priority channel frame hasnot been started (e.g., even if the lower priority channel frame hasbeen scheduled to transmit at a time earlier than the time at which aframe from a higher priority channel has been scheduled to betransmitted).

In various embodiments, the selective media access controller 700includes more than two channel access controllers. The CSMA/CAtechniques described above are implemented, for example, by each channelaccess controller accessing the state information of all other channelaccess controllers. When a contention issue (e.g., potential overlap ofthe transmission of both frames) is determined, the contention isresolved in accordance with a contention policy (e.g., first in/firstout, network priority, usage, application importance, and the like).

In various embodiments, differing PHY protocols (where the channelaccess to the physical layer is different for each network) are possibleas illustrated below with reference to FIG. 8. The differing PHYprotocols are used in combination with the differing MAC protocolsdisclosed above.

FIG. 8 is a signal diagram illustrating PHY layer protocolidentification in selective media access control in accordance withvarious embodiments of the disclosure. In various example scenarioshaving two or more networks, each such network can be selected where afirst network has a PHY protocol (and different MAC route) that isdifferent from the PHY protocol (and the associated MAC route) of asecond network that share a common communications medium. For example,the PHY layers of both the first network protocols and the secondnetwork protocols are operable to operate in a same frequency band(e.g., tone mask). Despite being operable to operate in the same (oroverlapping) frequency, the PHY-level protocol of the associated networkis identifiable by analyzing the preamble pattern. The associatednetwork itself is identifiable in response to the identification of thePHY-level protocol, for example, in implementations operating inaccordance with a different PHY-level protocol for each network operablefor accessing the shared communications medium. (In other embodiments,differing networks can use the same PHY-level protocol to share thephysical transmission medium.) Scenario 800 illustrates a transmissionby a first networked entity of a data frame 810 using a physical mediumcarrying communications in accordance with differing PHY protocols. Forexample, a processor is operable for receiving payload data of a firstmedia access control (MAC) frame and for receiving an indication of aselected network operable for transmitting the payload data of the firstMAC frame. The processor selects an appropriate MAC-level protocol inresponse to the indication of the selected network and queues thepayload data for transmission using data frame 810.

The data frame 810 includes a preamble 812 (e.g., for identifying thenetwork associated with data frame 810). After the preamble 812 istransmitted by the first networked entity, the first networked devicetransmits the remainder of the data frame 810, which normally includes aframe control header (FCH) 814 and the (e.g., data) payload 816. Thetransmission of the data frame 810 is typically followed by a responseinter-frame space (RIFS) 818.

A second networked entity identifies the particular PHY protocol used(and accordingly the associated network) by analyzing (e.g., decoding)the received preamble of data frame 810 and, in response, transmits anacknowledgement (ACK) frame 820 using network protocols (e.g., PHYprotocols) appropriate for the network identified by the receivedpreamble.

When the second networked entity receives the data frame 810, the PHYlayers of the second networked entity analyzes the received preamble 812to identify the associated network and decodes the FCH 814 and thepayload 816. in accordance with the identified network. The PHY layersof the second networked entity transfers information associated with thereceived packet (e.g., including the payload data and the identity ofthe identified network) to the MAC layer of the protocol associated withthe incoming packet. The MAC layers of second networked entity decodethe transferred information in accordance with the transferredinformation and passes the decoded information to higher levels of theassociated protocol stack over the MAC-layer route that is associatedwith the identified network.

The second networked entity generates an acknowledgement reply inresponse to the decoded information being passed to higher levels of theassociated protocol stack. The acknowledgement reply is (e.g.,generally) formed using the protocols in the MAC and PHY layersassociated with the identified network. For example, the secondnetworked entity transfers information related to the acknowledgementover a route through the MAC layers that are associated with theidentified network. The MAC layers associated with the identifiednetwork selects the PHY protocol that is associated with the identifiednetwork and transmits the ACK frame 820 in response.

The transmission of the ACK frame 820 terminates the RIFS 818 period.The ACK frame includes a preamble 822 (e.g., that includes informationidentifying the identified network) and a FCH 824. The transmission ofthe ACK frame 820 is followed by a contention inter-frame space (RIFS)828, during which time for example, any networked entity can attempt totransmit a new data frame.

The transmission of frames 810 and 820 are typically transmitted inaccordance with the separate channel access procedures performed byselective media access controllers such as selective media accesscontrollers 500 and 700. In an embodiment, a first network is operablein accordance with the IEEE P1901.2 protocol and a second network (e.g.,that shares the physical communications line with the first network) isoperable in accordance with the G3-PLC protocols. In variousembodiments, separate channel access procedures performed by selectivemedia access controllers are operable in scenarios in which the PHYlayer includes transmissions in which more than two protocols are usedfor transmitting data frames over two networks.

The various embodiments described above are provided by way ofillustration only and should not be construed to limit the claimsattached hereto. Those skilled in the art will readily recognize variousmodifications and changes that could be made without following theexample embodiments and applications illustrated and described herein,and without departing from the true spirit and scope of the followingclaims.

What is claimed is:
 1. A circuit, comprising: a memory operable forstoring payload data of a first media access control (MAC) frame and forstoring a first network tag in association with the first MAC frame; anda processor operable for selecting a MAC protocol route through a splitnetwork stack in accordance with the first network tag, wherein thesplit network stack includes at least two MAC protocol sublayersincluding a first MAC protocol sublayer corresponding to a first MACprotocol and a second MAC protocol sublayer corresponding to a secondMAC protocol, wherein the at least two MAC protocol sublayers areassociated with a common physical (PHY) layer of the split network stackand the first and second MAC protocols are different.
 2. The circuit ofclaim 1, wherein the first network tag is received from an applicationgenerating the payload data of the first MAC frame.
 3. The circuit ofclaim 2, wherein the first network tag indicates the first MAC protocolsublayer of the split network stack and the processor is operable totransmit the payload data of the first MAC frame in accordance with thefirst MAC protocol sublayer.
 4. The circuit of claim 3, wherein thememory is operable for storing payload data of a second media accesscontrol (MAC) frame and for storing a second network tag in associationwith the second MAC frame, wherein the second network tag indicates thesecond MAC protocol sublayer of the split network stack, and wherein theprocessor is operable to transmit the payload data of the second MACframe in accordance with the second MAC protocol sublayer.
 5. Thecircuit of claim 4, wherein the memory is operable for storing both thepayload data of the first MAC frame and the payload data of a second MACframe at the same time.
 6. The circuit of claim 4, comprising: a firststate machine operable for storing first state information generated fortransmitting the payload data of the first MAC frame in accordance withthe first MAC protocol sublayer; and a second state machine operable forstoring second state information generated for transmitting the payloaddata of the second MAC frame in accordance with the second MAC protocolsublayer.
 7. The circuit of claim 6, wherein the second state machine isresponsive to the first state information generated for transmitting thepayload data of the first MAC frame in accordance with the first MACprotocol sublayer.
 8. The circuit of claim 7, wherein the second statemachine is operable for scheduling a transmission of the payload data ofthe second MAC frame in accordance with the second MAC protocol sublayerresponsive to the first state information, such that collisions betweentransmitting the first MAC frame and the second MAC frame are prevented.9. The circuit of claim 7, wherein the payload data of the first MACframe and the payload data of the second MAC frame are transmitted usinga same physical transmission medium.
 10. The circuit of claim 4, whereinthe payload data of the first MAC frame is transmitted in accordancewith a first PHY-level protocol and the payload data of the second MACframe is transmitted in accordance with a second PHY-level protocol thatis different from the first PHY-level protocol.
 11. The circuit of claim4, wherein a PHY-level protocol of a received frame encapsulating thepayload data of the first MAC frame is identified by reading a preambleof the received frame and decoding header and payload data of thereceived frame in accordance with the identified PHY-level protocol. 12.A circuit, comprising: a processor operable for receiving payload dataof a first media access control (MAC) frame, for receiving an indicationof a selected network operable for transmitting the payload data of thefirst MAC frame, and for selecting a MAC-level protocol in response tothe indication of the selected network wherein the processor is operableto select a MAC-level protocol route through a split network stack inaccordance with the indication of the selected network, wherein thesplit network stack includes at least two MAC protocol sublayersincluding a first MAC protocol sublayer corresponding to a firstMAC-level protocol and a second MAC protocol sublayer corresponding to asecond-level MAC protocol, wherein the at least two MAC protocolsublayers are associated with a common physical (PHY) layer of the splitnetwork stack, the first and second MAC-level protocols are different,and wherein the selected MAC-level protocol is the first MAC-levelprotocol when the selected network corresponds to the first MAC-levelprotocol and is the second MAC-level protocol when the selected networkcorresponds to the second MAC-level protocol; and a coupler for couplingpower line communications (PLC) signals through a communications medium,wherein the PLC signals include the payload data of the first MAC frame,and wherein the communications medium is operable for carrying signalsof a plurality of networks from which the selected network is selected.13. The circuit of claim 12, wherein the coupler is operable forreceiving PLC signals from one of the plurality of networks coupled tothe communications medium and for generating the first MAC frame inresponse to the received PLC signals.
 14. The circuit of claim 12,wherein the processor is operable for selecting a PHY-level protocol fortransmitting the payload data of the first MAC frame in response to theindication of the selected network.
 15. The circuit of claim 12, whereinthe processor is operable for identifying a PHY-level protocol inresponse to receiving a PLC signal, wherein the PLC signal includes thepayload data of the first MAC frame, and wherein the selected network isidentified in response to the analyzing the PLC signal.
 16. A method,comprising: storing payload data of a first media access control (MAC)frame; receiving a first network tag in association with the first MACframe; and selecting a first MAC protocol route in a split network stackin accordance with the first network tag, wherein the split networkstack includes at least two MAC protocol sublayers including a first MACprotocol sublayer corresponding to a first MAC protocol and a second MACprotocol sublayer corresponding to a second MAC protocol; wherein the atleast two MAC protocol sublayers are associated with a common physical(PHY) layer of the split network stack, wherein the first and second MACprotocols are different, and wherein the first network tag indicates thefirst MAC protocol sublayer of the split network stack and the first MACprotocol route includes the first MAC protocol sublayer.
 17. The methodof claim 16, comprising: storing payload data of a second MAC frame;receiving a second network tag in association with the second MAC frame,wherein the second network tag indicates the second MAC protocolsublayer, and wherein the second network tag is associated with a secondMAC protocol route in the split network stack that is different from thefirst MAC protocol route and includes the second MAC protocol sublayer.18. The method of claim 17, comprising transmitting the payload data ofthe first MAC frame in accordance with a first MAC protocol sublayerassociated with the first network tag and transmitting the payload dataof the second MAC frame in accordance with a second MAC protocolsublayer associated with the second network tag.
 19. The method of claim17, wherein the payload data of the first MAC frame is transmitted inaccordance with a first PHY-level protocol and the payload data of thesecond MAC frame is transmitted in accordance with a second PHY-levelprotocol that is the same as the first PHY-level protocol, wherein thefirst MAC frame is transmitted using a first channel access mechanismand the second MAC frame is transmitted using a second channel accessmechanism simultaneously with transmitting the first MAC frame using thefirst channel access mechanism.